Ignition spark tester including compression release vent



Nov. 25, 1969 v. w. CLONING'ER 3,480,853

IGNITION SPARK TESTER INCLUDING COMPRESSION RELEASE VENT Filed June 28, 1967 16 F}: If 14\ g 15 )(I II 185' 14 I! Z1 6! 5 J6 IN VE N TOR. KER/VON M CAO/V/IVGAFE.

bu 91M ATTORNEY United States Patent 3,480,853 IGNITION SPARK TESTER INCLUDING COMPRESSION RELEASE VENT Vernon W. Cloninger, 609 S. 9th, Bozeman, Mont. 59715 Filed June 28, 1967, Ser. No. 649,731 Int. Cl. GOlr 13/42 US. Cl. 324-17 1 Claim ABSTRACT OF THE DISCLOSURE A spark plug ignition tester comprising a specially constructed spark plug having compression vents in its base and a spark gap on its stem so that the engine may be operated to test the efficiency of the spark at each spark plug hole of the engine.

BACKGROUND OF THE INVENTION (1) The field of this invention lies in ignition systems and testing apparatus for internal combustion engines, and is particularly directed to a device for testing the efficiency of the spark at the spark plug opening of the engine.

,.(2) Heretofore it has been necessary for two persons to make the test particularly on internal combustion engines not having automatic power starting for rotating the engine.

" Further, it has been difiicult tomake an exact test at the spark plug hole and to be able to do it without excessive compression such as in small single cylinder engines which must be rotated by hand.

SUMMARY OF THE INVENTION In this invention it is an object to provide a test spark plug specially designed for immediately determining the efliciency of the spark at the spark plug opening of the engine.

Still another object of this invention is to provide a test spark plug especially adapted for use in conjunction with outboard motors, lawn mower engines and other small stationery single or multiple cylinder engines without the requirement of more than one operator to effect an eflicient result.

Still another object of this invention is to provide a specially constructed test spark plug which may be applied to the spark plug threaded hole of the engine and which relieves the compression of the cylinder while at the same time indicating clearly and easily visible the spark condition of the operation of the ignition of the engine.

It is also an object of this invention to maintain the test plug in proper operative condition at all times and to make it adjustable for wear or change in its characteristics during use.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of the test spark plug incorporating the features of this invention greatly enlarged.

FIG. 2 is a plan view of the test spark plug shown in FIG. 1.

FIG. 3 is a bottom view of the test spark plug shown in FIGS. 1 and 2.

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DESCRIPTION OF THE PREFERRED EMBODIMENT As an example of a preferred embodiment of the invention, there is shown a test spark plug comprising a base 10having a threaded end 11 adapted to be inserted inthe spark plug hole of an internal combustion engine. A bore12 is formed in the base 10 communicating with the cylinder chamber of the engine and radially disposed compression vents 13 formed in the base 10 connecting the bore 12 to atmosphere when the test plug is inserted in' the spark plug hole of the engine.

Projecting upwardly from the base :and fixed thereto is a stem 14a of dark colored insulative material such as plastic or ceramic in and on top of which is fixed a threaded stem 14 over which is placed the upper spark gap piece 15 which is secured in place by the usual spark plug high tension terminal 16. The upper spark gap piece 15 has a turned down end 17 terminating in the downwardly facing spark gap surface 18a. The lower grounded spark gap piece 18 has a lower threaded end 19 adjustably mounted in the mating vertically disposed threaded bore 20 formed in the base 10 and has a top spark gap forming surface 21.

The compression relief vents 13 enable one man to check the spark on an engine, a job that usually requires two men. The relief vents 13 relieve the compression so that the person checking the spark on hand-starting types of engines is not pulling the hand-starter rope against compression. The one-quarter inch gap is the preferred setting for all small engines. If the spark jumps the onequarter inch gap, the spark or magneto is good. If not, the magneto needs overhauling or adjusting, or should be taken to the proper repair shop. In time, the spark gap surfaces will burn from one side of the gap to the other. They then have to be filed lightly. As the rod is filed, it can be screwed out of the threaded bore 20 to maintain the one-quarter inch gap. Hence, the threads on the lower one-eighth inch brass conductor.

To use the device, the user removes the regular spark plug from the small engine to be checked, screwing this test spark plug in its place. The spark wire is fastened on the test plug terminal 16 in the same place it was fastened onto the spark plug. With the compression relief vents 13 in the test plug, it is easy for one person to spin the small engine fast enough to check the spark. To check the magneto without the test plug actually involves two persons, one to hold the spark Wire and another to pull the starter and hold the engine firmly. The insulative stern 14a of the test plug is made of a dark colored ceramic or plastic, the dark color making the spark more visible during testing.

I claim:

1. An ignition spark tester for an internal combustion engine comprising in combination:

A. a base,

B. means on said base for securing the same in the spark plug hole of an internal combustion engine,

C. an insulative stem fixed to and upstanding from said base,

D. a threaded stem fixed to and upstanding from the top of said insulative stem,

E. a regular spark plug high tension terminal mounted on said threaded stem,

F. an upper spark plug gap piece secured to and electrically connected with said high tension terminal having a downwardly facing spark gap surface,

G. a lower spark gap piece fixed to and electrically grounded to said base having an upwardly facing spark gap surface aligned with said spark gap face of said upper spark gap piece,

H. and a compression vent passageway in said base communicating between the engine cylinder chamber and atmosphere to relieve engine compression restraint in turning over the engine when utilizing said ignition spark tester.

References Cited UNITED STATES PATENTS Brandquist 324-18 DeVilbiss 32417 Opsahl 32417 Houghton 324-17 Willis 3l24-17 Thesing 32417 RUDOLPH v. ROLINEC, Primary Examiner M. J. LYNCH, Assistant Examiner 

